syntax - JavaScript property access: dot notation vs. brackets? -

other obvious fact first form use variable , not string literal, there reason use 1 on other, , if under cases?

in code:

// given: var foo = {'bar': 'baz'};  // var x = foo['bar'];  // vs.  var x = foo.bar; 

context: i've written code generator produces these expressions , i'm wondering preferable.

(sourced here.)

square bracket notation allows use of characters can't used dot notation:

var foo = myform.foo[]; // incorrect syntax var foo = myform["foo[]"]; // correct syntax 

secondly, square bracket notation useful when dealing property names vary in predictable way:

for (var = 0; < 10; i++) {   somefunction(myform["mycontrolnumber" + i]); } 

roundup:

• dot notation faster write , clearer read.
• square bracket notation allows access properties containing special characters , selection of properties using variables

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another example of characters can't used dot notation property names contain dot.

for example json response contain property called bar.baz.

var foo = myresponse.bar.baz; // incorrect syntax var foo = myresponse["bar.baz"]; // correct syntax